1. Field of the Invention
This invention relates generally to a postage value calculation system and more particularly to an apparatus and method for improved postage value calculations through an enhanced information storage and retrieval system.
2. Brief Description of the Prior Art
Various devices and methods for calculating postage have been proposed heretofore. These systems varied from a simple postage value storage table as shown in U.S. Pat. No. 3,635,297 issued Jan. 18, 1972 to more elaborate postage value systems featuring the use of microprocessors as illustrated in U.S. Pat. No. 3,978,457 by Frank P. Check, Jr. et al, issued Aug. 31, 1976 and assigned to the assignee of the present invention.
In these prior systems, the storage of postage rate data has been a formidable problem. In systems which included memories comprised of storage tables, a great amount of memory space was required to provide data necessary in many postal variations including destination, zone, priority, class, carrier type, etc. When a change in postal rates was effected by the postal service, the memory units had to be changed at considerable expense in time, money and inconvenience. In postage value calculators of more elaborate systems, rate changes often required reprogramming or software change.
Further problems have been encountered with regard to the allocation of rate and other data in memory systems. Memory allocation maps were employed for graphically defining memory systems to specify areas reserved for particular data. Generally, data for use in specific subroutines were stored at consecutive address locations. This practice often resulted in gaps of available storage locations for future expansion. Furthermore, when postal rate changes necessitated the addition of new postal rate data to be accessed during a particular subroutine, entire memory blocks were often required to be revised and reallocated. Rate changes often necessitated the revision of data stored at further locations which may have been used to define data parameters such as weight range boundaries, memory length or the system directory itself.
Although indirect addressing techniques provide some degree of flexibility, programming changes were often required in conjunction with newly stored data to be indirectly addressed. Such programming changes increased the possibility of system errors.